// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef MEDIA_BASE_AUDIO_RENDERER_SINK_H_
#define MEDIA_BASE_AUDIO_RENDERER_SINK_H_

#include <stdint.h>

#include <string>

#include "base/callback.h"
#include "base/memory/ref_counted.h"
#include "media/base/audio_bus.h"
#include "media/base/audio_parameters.h"
#include "media/base/output_device_info.h"
#include "url/origin.h"

namespace media {

// AudioRendererSink is an interface representing the end-point for
// rendered audio.  An implementation is expected to
// periodically call Render() on a callback object.

class AudioRendererSink
    : public base::RefCountedThreadSafe<media::AudioRendererSink> {
public:
    class RenderCallback {
    public:
        // Attempts to completely fill all channels of |dest|, returns actual
        // number of frames filled. |prior_frames_skipped| contains the number of
        // frames
        // the consumer has skipped, if any.
        // The |delay| argument represents audio device output latency,
        // |delay_timestamp| represents the time when |delay| was obtained.
        virtual int Render(base::TimeDelta delay,
            base::TimeTicks delay_timestamp,
            int prior_frames_skipped,
            AudioBus* dest)
            = 0;
        // Signals an error has occurred.
        virtual void OnRenderError() = 0;

    protected:
        virtual ~RenderCallback() { }
    };

    // Sets important information about the audio stream format.
    // It must be called before any of the other methods.
    virtual void Initialize(const AudioParameters& params,
        RenderCallback* callback)
        = 0;

    // Starts audio playback.
    virtual void Start() = 0;

    // Stops audio playback and performs cleanup. It must be called before
    // destruction.
    virtual void Stop() = 0;

    // Pauses playback.
    virtual void Pause() = 0;

    // Resumes playback after calling Pause().
    virtual void Play() = 0;

    // Sets the playback volume, with range [0.0, 1.0] inclusive.
    // Returns |true| on success.
    virtual bool SetVolume(double volume) = 0;

    // Returns current output device information. If the information is not
    // available yet, this method may block until it becomes available.
    // If the sink is not associated with any output device, |device_status| of
    // OutputDeviceInfo should be set to OUTPUT_DEVICE_STATUS_ERROR_INTERNAL.
    // Must never be called on the IO thread.
    virtual OutputDeviceInfo GetOutputDeviceInfo() = 0;

    // If DCHECKs are enabled, this function returns true if called on rendering
    // thread, otherwise false. With DCHECKs disabled, it returns true. Thus, it
    // is intended to be used for DCHECKing.
    virtual bool CurrentThreadIsRenderingThread() = 0;

protected:
    friend class base::RefCountedThreadSafe<AudioRendererSink>;
    virtual ~AudioRendererSink() { }
};

// Same as AudioRendererSink except that Initialize() and Start() can be called
// again after Stop().
// TODO(sandersd): Fold back into AudioRendererSink once all subclasses support
// this.

class RestartableAudioRendererSink : public AudioRendererSink {
protected:
    ~RestartableAudioRendererSink() override { }
};

class SwitchableAudioRendererSink : public RestartableAudioRendererSink {
public:
    // Attempts to switch the audio output device associated with a sink.
    // Once the attempt is finished, |callback| is invoked with the
    // result of the operation passed as a parameter. The result is a value from
    // the media::OutputDeviceStatus enum.
    // There is no guarantee about the thread where |callback| will be invoked.
    virtual void SwitchOutputDevice(const std::string& device_id,
        const url::Origin& security_origin,
        const OutputDeviceStatusCB& callback)
        = 0;

protected:
    ~SwitchableAudioRendererSink() override { }
};

} // namespace media

#endif // MEDIA_BASE_AUDIO_RENDERER_SINK_H_
